Quorum sensing controls the synthesis of virulence factors by modulating rsmA gene expression in Erwinia carotovora subsp carotovora
Quorum sensing controls the synthesis of virulence factors by modulating rsmA gene expression in Erwinia carotovora subsp carotovora
复制标题
法定人数感应通过调节 Erwinia carotovora subsp carotovora 中 rsmA 基因的表达来控制毒力因子的合成
DOI：
10.1007/s004380000413
复制
发表时间：
2001-04-01
影响因子：
3.1
通讯作者：
Mäe, A
中科院分区：
文献类型：
--
作者：
Koiv, V;Mäe, A
胡萝卜软腐欧文氏菌Erwinia carotovora subsp.胡萝卜软腐菌（Ecc）主要通过许多胞外植物细胞壁降解酶（PCWDE）（也称为毒力因子）引起疾病。多氯WDEs的产生由扩散信号分子N-酰基高丝氨酸内酯以群体密度依赖的方式协同激活（“群体感应”）。ExpI是负责合成HSL的酶。Rsm系统对多氯联苯WDE的生产起到负面调节作用。它包括三个组成部分：RsmA是一种促进mRNA降解的RNA结合蛋白; rsmB是一种独特的调节RNA，RsmC正调节rsmA的表达，负调节rsmB的表达。我们在这里报告，在Ece菌株SCC 3193的expI敲除突变体中，rsmA和rsmB RNA的水平与野生型菌株相比显著增强，而rsmC转录物的水平不受影响。expI菌株中rsmA转录的增加抑制了PCWDE的产生，这反过来导致了该突变体的无毒表型。在expI（-）突变体中，加入外源HSL导致rsmA和rsmB转录抑制至野生型水平，而rsmC的表达不受影响。综上所述，这些数据表明，HSL影响rsmA的表达，并且这种作用不是由RsmC介导的。这种特定的效果和先前的证明，HSL是必需的PCWDE生产Ece支持的假设，即在Ecc中的群体感应调节，与大多数其他系统已经描述，需要HSL抑制rsmA转录，这反过来又导致激活PCWDE生产。一个模型，解释了如何HSL控制生产的PCWDEs通过调节rsmA的表达。
The plant-pathogenic bacterium Erwinia carotovora subsp. carotovora (Ecc) causes disease mainly by means of a number of extracellular plant cell wall-degrading enzymes (PCWDEs), also referred to as virulence factors. The production of PCWDEs is coordinately activated by the diffusible signal molecule N-acyl-homoserine lactone (HSL) in a population density-dependent manner ("quorum sensing"). ExpI is the enzyme responsible for the synthesis of HSL. The Rsm system negatively regulates the production of PCWDEs. It includes three components: RsmA is an RNA-binding protein which promotes mRNA decay; rsmB is a unique regulator RNA, and RsmC regulates expression of rsmA positively and of rsmB negatively. We report here that in an expI knockout mutant of Ece strain SCC3193, the levels of rsmA and rsmB RNA are remarkably enhanced in comparison to the wild-type strain, while the level of the rsmC transcript is not affected. The increase in transcription of rsmA in the expI strain represses production of PCWDEs, which in turn leads to the avirulent phenotype of this mutant. In the expI(-) mutant, addition of exogenous HSL caused repression of rsmA and rsmB transcription to the wildtype level, whereas the expression of rsmC was not affected. Taken together, these data suggest that HSL affects the expression of rsmA, and that this effect is not mediated by RsmC. This specific effect and the previous demonstration that HSL is required for PCWDE production in Ece support the hypothesis that regulation by quorum sensing in Ecc, in contrast to most other systems already described, requires HSL to repress rsmA transcription, which in turn leads to the activation of PCWDE production. A model is presented that explains how HSL controls the production of PCWDEs by modulating the expression of rsmA.